diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 76170c3201..9f3a26a123 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -53,6 +53,14 @@ using node::UpdateTime;
  * If 'height' is nonnegative, compute the estimate at the time when a given block was found.
  */
 static UniValue GetNetworkHashPS(int lookup, int height, const CChain& active_chain) {
+    if (lookup < -1 || lookup == 0) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid nblocks. Must be a positive number or -1.");
+    }
+
+    if (height < -1 || height > active_chain.Height()) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Block does not exist at specified height");
+    }
+
     const CBlockIndex* pb = active_chain.Tip();
 
     if (height >= 0 && height < active_chain.Height()) {
@@ -97,7 +105,7 @@ static RPCHelpMan getnetworkhashps()
                 "Pass in [blocks] to override # of blocks, -1 specifies since last difficulty change.\n"
                 "Pass in [height] to estimate the network speed at the time when a certain block was found.\n",
                 {
-                    {"nblocks", RPCArg::Type::NUM, RPCArg::Default{120}, "The number of blocks, or -1 for blocks since last difficulty change."},
+                    {"nblocks", RPCArg::Type::NUM, RPCArg::Default{120}, "The number of previous blocks to calculate estimate from, or -1 for blocks since last difficulty change."},
                     {"height", RPCArg::Type::NUM, RPCArg::Default{-1}, "To estimate at the time of the given height."},
                 },
                 RPCResult{
diff --git a/test/functional/rpc_blockchain.py b/test/functional/rpc_blockchain.py
index 53163720bb..cba12e6fe0 100755
--- a/test/functional/rpc_blockchain.py
+++ b/test/functional/rpc_blockchain.py
@@ -451,6 +451,35 @@ class BlockchainTest(BitcoinTestFramework):
         # This should be 2 hashes every 10 minutes or 1/300
         assert abs(hashes_per_second * 300 - 1) < 0.0001
 
+        assert_raises_rpc_error(
+            -8,
+            "Block does not exist at specified height",
+            lambda: self.nodes[0].getnetworkhashps(100, self.nodes[0].getblockcount() + 1),
+        )
+        assert_raises_rpc_error(
+            -8,
+            "Block does not exist at specified height",
+            lambda: self.nodes[0].getnetworkhashps(100, -10),
+        )
+        assert_raises_rpc_error(
+            -8,
+            "Invalid nblocks. Must be a positive number or -1.",
+            lambda: self.nodes[0].getnetworkhashps(-100),
+        )
+        assert_raises_rpc_error(
+            -8,
+            "Invalid nblocks. Must be a positive number or -1.",
+            lambda: self.nodes[0].getnetworkhashps(0),
+        )
+
+        # Genesis block height estimate should return 0
+        hashes_per_second = self.nodes[0].getnetworkhashps(100, 0)
+        assert_equal(hashes_per_second, 0)
+
+        # Ensure long lookups get truncated to chain length
+        hashes_per_second = self.nodes[0].getnetworkhashps(self.nodes[0].getblockcount() + 1000)
+        assert hashes_per_second > 0.003
+
     def _test_stopatheight(self):
         self.log.info("Test stopping at height")
         assert_equal(self.nodes[0].getblockcount(), HEIGHT)